Novartis announced that the FDA has approved Itvisma® (onasemnogene abeparvovec-brve) for the treatment of children two years and older, teens and adults living with spinal muscular atrophy (SMA) with a confirmed mutation in the survival motor neuron 1 (SMN1) gene, making it the first and only gene replacement therapy available for this broad population. Itvisma is uniquely designed to address the genetic root cause of SMA with a one-time fixed dose that does not need to be adjusted for age or body weight. By replacing the SMN1 gene, Itvisma can improve motor function, offering the potential to reduce the need for chronically administered treatment associated with other available therapies for this population.
“The FDA’s approval of intrathecal onasemnogene abeparvovec is a game-changing advance, expanding the use of transformational gene replacement therapy for SMA across age groups,” said John W. Day, MD, PhD, Professor of Neurology and Pediatrics, Director, Division of Neuromuscular Medicine at Stanford University School of Medicine, and Co-Director of Stanford’s Neuro IGNITE Center. “This achievement is not only a significant step forward for SMA – it also signals new possibilities for the broader field of neurological disorders and genetic medicine.”
The approval of Itvisma is based on data from the registrational Phase lll STEER study and supported by the open-label Phase lllb STRENGTH study. Itvisma showed statistically significant improvements in motor function and stabilization of motor abilities typically not seen in the natural history of the disease, with effects sustained over 52 weeks of follow-up. Additionally, Itvisma demonstrated a safety profile with adverse events that were consistent across both studies. The most common adverse events in the STEER study were upper respiratory tract infection and pyrexia, and the most common adverse events in the STRENGTH study were common cold, pyrexia, and vomiting. These data were presented at the 2025 Muscular Dystrophy Association (MDA) Clinical and Scientific Conference.
“This new route of administration for a single dose of gene replacement therapy can mean so much more than what is measured by numbers on a functional motor scale – it could mean greater independence and freedom in activities of daily life,” said Kenneth Hobby, President, Cure SMA. “The SMA disease landscape has dramatically changed over the last six years, when the first gene therapy was approved. This is another welcome advancement, and it represents real progress in expanding access for many older patients and addressing the unmet needs that remain in our community.”
SMA is a rare, genetic neuromuscular disease caused by a mutated or missing SMN1 gene. The SMN1 gene is responsible for producing most of the SMN protein a body needs for muscle function, including breathing, swallowing and basic movement. Without it, motor neurons are irreversibly lost, leading to progressive, debilitating muscle weakness. A second gene, the SMN2 gene, produces a small fraction (~10%) of functional SMN protein compared with the SMN1 gene. Individuals with more copies of the SMN2 gene generally have a less severe form of SMA than those with fewer copies.
Approximately 9,000 people in the US live with SMA, and though there have been advancements in treating the disease, unmet needs remain for older children, teens, and adults in preserving motor neurons and maintaining physical strength.
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